Sanding head



Aug. 25, 1942. O AMSTUZ 2,294,064

SANDING HEAD Filed Aug. 4, 1940 6 Sheets-Sheet 1 J0 HN 7 F7M5 71/2 1942-.1. o. AMSTUZ 2,294,064

SANDING HEAD Filed Aug. 4, 1940 6 Sheets-Sheet 2 JaH/v HMSTL/Z v PLF'OLMAug. 25, 41942. J. o. AMSTUZ 2,294,064

SANDING HEAD Filed Aug. 4. 1940 6 Sheets-Sheet 5 JaH/v U HME UZ g- 1942-J. o. AMSTUZ SANDING HEAD Filed Aug. 4. 1940 6 Sheets-Sheet 4 w/gwwm/ AAug. 25, 1942.

J. o. AMSTUZ. 2,294,064

SANDING HEAD Filed Aug. 4, 1940 6 SheetsSheet 5 V aww/whw JaH/v U 5W5TL/Z Aug. 25, 1942. J. o. AMST UZ, 2,294,064

SANDING HEAD Filed Aug. 4, 1940 6 Sheets-Sheet 6 l we I v JoH/v Z7.HMsTL/z Patented Aug. 25, 1942 SANDING HEAD John 0. Amstuz, Troy, N. Y.,assignor to Behr- Manning Corporation, Troy, N. Y., a corporation ofMassachusetts Application August 4, 1940, Serial No. 351,317

' 2 Claims. (01. 51-191) The invention relates to sanding heads.

One object of the invention is to provide a sanding head adapted to holda light weight piece of sandpaper in the form of a disc. Another objectof the invention is to provide a sanding head for the efficientlubrication of a sanding disc secured to the head. Another object of theinvention is to provide practical and eflicient clamps to clamp a lightweight sanding disc to a head. Another object of the invention is toprovide a complete sanding head with a sandpaper disc, including acushioning support and spider with radially extending arms for holding alight weight piece of sandpaper, preferably of the waterproof variety,over a large radial distance.

Another object of the invention is to provide an efiicientinstrumentality for surfacing such objects as automobile bodies, forexample, after they have received priming coats. Another object of theinvention is to provide a sanding disc and head for sanding softmaterials which shall not load up. Another object of the invention is todistribute water to abrasive paper in the form of a disc while it issanding in an efficient and thorough manner. Another object of theinvention is to provide an apparatus for the centrifugal distribution ofwater over the face of sandpaper during a disc sanding operation.

Another object of the invention is to provide a head for the mounting ofthin discs of waterproof sandpaper so that they will not tear in spite'of the use of high speeds, and to provide a copious supply of lubricantand clearance spaces so that the waterproof sandpaper will not load upwith any soft material, such as paint, which is being sanded. Otherobjects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction,combinations of elements, arrangements of parts, and in the severalsteps and relation and order of each of said steps to one or more of theothers thereof, all as will be illustratively described herein, and thescope of the application of which will be indicated in the followingclaims.

In the accompanying drawings showing several possible embodiments of themechanical features of this invention:

Figure 1 is a plan view on a reduced scale, of a piece of sandpaper,preferably of the waterproof variety, adapted to be held by any one ofthe heads of the present invention.

Figure 2 is the front elevation of a head constructed in accordance withthe present invention.

Figure 3 is a cross-sectional view taken on line 3-3 of Figure 2.

Figure 4 is a fragmentary sectional view taken on line 4-4 of Figure 2.

Figure 5 is a front elevation of a modified form of sanding head.

Figure 6 is a sectional view taken along line 66 of Figure 5.

Figure 7 is a. front elevation of another modification of the invention.

Figure 8 is a cross-sectional view taken on line 8-8 of Figure 7.

Figure 9 is a front elevation of another modification of the invention.

Figure 10 is a cross-sectional view taken on line Ill-ill of Figure 9.

Figure 11 is a front elevation of another modification of the invention.

Figure 12 is a sectional view taken on line |2l2 of Figure 11.

Figure 13 is a fragmentary peripheral view of the modification ofFigures 11 and 12.

Figure 14 is an elevation of still another modiflcation of theinvention.

Figure 15 is a sectional view taken on line l5-l5 of Figure 14.

The disc holding heads of the invention are adapted to be attached toexisting machines involving a motor driven flexible hollow shaft withmeans for supplying water through the hollow shaft so that the waterwill emerge at the center of the sanding disc and lubricate it.

Referring now to Figure 1, I provide an annular disc 20 of sandpaper.This has an internal diameter identified as 2| and an external diameteridentified as 22. According to the preferred form of the presentinvention the annular disc 20 consists of a sheet of thin, flexiblesandpaper cut to the shape shown. I prefer to use flexible waterproofsandpaper involving a paper backing suitably treated or impregnated withsemi-drying oils, drying oils or resins, so that the backing will notdeteriorate in use, even under conditions of sustained immersion inwater throughout the effective life of the abrasive coating. Within thescope of the invention, any suitable abrasive grit may be used, such asfused alumina, silicon carbide, garnet, quartz (flint) or crushed glass,but for many sanding operations 1 of the type indicated, silicon carbideis preferred. Waterproof sandpaper usually involves the use of fine gritabrasive, such as grit size or finer. For a typical embodiment of thepresent invention I may use grit sizes, ranging between' #240 and #360.The abrasivegrit is secured to the waterproofed paper by a waterproofadhesive binder such as suitable varnishes or resins as is now known inthe art. Thus, according to the preferred form of the present invention,the disc 20 is made from a typical piece of thin, light weight,waterproof sandpaper, for example. weights known as A weight or Cweight, as distinguished from the heavy fibre backed discs withrelatively coars abrasives which have been used in the prior art withapparatus for water sanding of the type indicated.

Referring now to Figure 3, the head therein illustrated comprises acircular adapter 25 having a central boss 26 internally threaded at 21for attachment to a flexible hollow shaft which may be rotated andthrough which water is supplied. The adapter 25 is fastened by means ofscrews 28 to an annular metal backing plate 29.

Referring now to Figures 2, 3 and 4, an an-.

nular disc of soft rubber 30 is cemented, as by means of any suitablecement for attaching rubber to metal, to the annular metal backing plate29. This disc 30 is preferably made with rubber vulcanized with a smallamount of sulphur and is, therefore, a flexible cushioning or deformablematerial as distinguished from ebonite. Any other material of the samenature, such as synthetic rubbers, chloroprene or neoprene, havingsimilar physical properties may be substituted.

Referring especially to Figure 4, extending in an axial direction fromthe boss 26 of the adapter 25 are a pair of identical pins 3| which arespaced at equal distances from the axis of the adapter 25 and areirremovably fastened to the adapter. These pins 3| have wide cut-outs 32facing the center of the adapter, leaving shoulders 33 for grippingengagement with cams to be described.

I further provide a spider assembly for holding the sandpaper disc 20against the annular disc 30, which comprises a central hub plate 34having a pair of holes 35 for mounting the entire spider assembly uponthe pins 3|, a plurality of radial arms 36 rigidly secured to the hubplate 34, and a rotatable circular cam plate 31. Cam plate 31 interfitswith the central hub plate 34 and is rotatable and is prevented fromcoming out by means of a ring 38 fitting in a groove in the cam plate.The cam plate 31 has a pair of wedge cams 46. The cam plate 31 can beturned so that the wedge earns 46 are clear of the holes 35 and then theentire spider assembly can be placed in position upon the pins 3|. Afterthe spider assembly has been thus placed in position, the rotatable camplate can be rotated, thus moving the wedge cams 46 into the cutouts 32and causing the high points of the cams to engage the shoulders 33.Preferably, shoulders 33 are V shaped in front elevation, formingvirtually points which fit in depressions 4| (shown in Figure 3) in thehigh points of the cams 46. A stop pin 42 may be provided in the hubplate 34 for limiting the rotation of the cam plate 31 to the exactposition where the points of the shoulders 33 coincide with thedepressions 4|.

The cam plate 31 has a central hole '43 of irregular shape to fit asuitable end wrench. This may be star shaped, as shown, which will takea T shaped square end wrench whereby the cam plate can readily berotated.

The adapter 25 is mounted on the end of a flexible hollow shaft as abovestated and when it-is desired to secure the sandpaper disc 20 to thehead, the operator first removes the entire spider assembly which may bedone by holding the entire unit and turning the cam plate 31 to move thewedge cams 40 out of the cut-outs 32, using an end wrench in theirregular hole 43. Thereupon an annular sheet of. sandpaper 26 is placedupon the annular disc of soft rubber 36 co-axial therewith and then thespider as-- sembly is again placed upon the pins 3|, and by means of thewrench, the cam plate 31 is turned to lock the parts together. As shownin Figures 2 and 3 I provide relatively deep radial recesses 45 in theannular soft rubber disc 36 in which the spider arms 36 fit. When the.parts are put together as described, the disc 20 is bent out of a planeto conform to the surface of the rubber disc 30 and fits in the radialrecesses 45 conforming to the surface thereof. I preferably providespikes 46 extending laterally from the radial arms 36 to pin thesandpaper in place, these spikes perforating the sandpaper and extendinginto the deformable soft rubber, thus the sandpaper, whose internaldiameter 2| and whose external diameter 22 may be approximately the sameas the respective internal and external diameters of the softrubberannular disc 30, is firmly but releasably held by the rubber discand conforms to its irregular surface, that is to say, depressions orgrooves are formed in the sandpaper and sandpaper is everywhere backedup by the soft rubber. While I have shown four spider arms 36 and fourradial recesses 45, a greater or lesser number might be employed withinthe scope of the invention.

I have found that despite the light weight of the sandpaper and despitethe use of the apparatus with fairly heavy work at high speeds up to1800 R. P. M. for discs whose overall diameter is 8 inches, sandpaperdoes not go to pieces nor tear and will last through the effectiveabrading life of the abrasive material thereof. The tool may be used inmany sanding operations and it is preferably used wet, that is to say,water is introduced through the hollow, flexible shaft, through thehollow boss 26 and through the irregular hole 43 and then by centrifugalforce spreads over the sanding disc. The water has a tendency to followthe radial recesses 45 but largely on the abrasive side or outside ofthe sandpaper, that is to say, along the radial arms 36. The radial arms36 are not so large that they entirely fill the radial recesses 45 andin fact, as shown, they fill but a small part thereof. Radial groovesare thus provided for water to move centrifugally along the abrasivesurface of the sandpaper, and thus a copious supply of water can bedelivered to the abradingoperation and is most effective forlubricating. The clearance provided by the grooves or recesses formed inthe sandpaper itself prevents loading of the sandpaper and prolongs itslife.

Referring now to Figures 5 and 6, a modification of the invention isshown in which the spider may be placed in position and removed simplyby squeezing together a pair of levers. The circular adapter 25 has apair of rigidly attached pins 50 having cut-outs in their sides adaptedto cooperate with levers 5| mounted on pins 52 extending axially fromcenter hub plate 53. Center hub plate 53 has radial arms 54 fitting inthe radial recesses 45 in order to hold the annular disc of sandpaper 20in place. Springs 55 extending between the anchorages of the arms 54 andthe ends of the levers 5| urge the levers into engaging position. Thehub plate 53 has holes 56 fitting over the pins 50 which may be taperedat the outer ends. Thus for inserting the spider it is only necessary toplace it over the pins 50 and push. For releasing the spider it issuflicient to squeeze the inner ends of the levers 5| toward each otherand pull.

Referring to Figures 7 and 8, another modification of the invention isshown, the action of engaging and disengaging, however, being somewhatsimilar to that of the modification of Figures 5 and 6. The adapter is alarge plate 60 to which the annular rubber disc 6| may be cemented.Suitably secured to the front side of the plate 60 is a block 62 havingrectangular cutouts 63 for the reception of latches 64 mounted on pins65 extending across the block 62. Spring 56 urges the latches 64 apartand stops pins 61 and holds them from moving beyond a certain position.The spider assembly is in the form of a ring I with a square hole 1| andarm I2. Cushioning springs I3 are provided to hold the ring I0 firmlyagainst the latches 64; thus the spider may be snapped into position bypushing the arms I2 into the radial recesses 45 and the spider may bereleased by pressing the latches 54 together with the fingers. In theembodiment of Figures '7 and 8 water enters through a central hole I inthe block 62 and moves radially through the recesses or depressions 45as in all the embodiments of the-invention.

Referring now to Figures 9 and 10, therein is shown an embodiment inwhich the adapter 80 is a cylindrical block having a pair of spacedthreaded holes 8| for attachment to a shaft with a flanged head by meansof screws. As in all cases, a central hole 82 is provided to conveywater to the sandpaper. A thin metal plate 83 has an annular disc 84 ofsoft rubber with radial recesses or depressions 45 suitably attached toit as by rubber cement. The metal plate 83 is likewise attached to theadapter 80 as by screws 86. Forked posts 8'! are attached to the plate83 at spaced positions as shown, and these receive wires 88 preferablypivotally attached thereto. Integrally formed with the adapter block 80is a cylindrical projection 89 having radial arms 99 with under-cutgrooves 9|. The ends of the pins fit into grooves 9I. The pins can beflexed sidewise to clear the arms 90 and then swing outwardly to allowthe sandpaper to be placed in position. This clamping device operates inthe nature of a safety pin.

Referring now to Figures 11, 12 and 13, an adapter block 95 has cut-outs96 for receiving wires 91 pivotally mounted therein by means of pins 98.The outer ends of the wires 91 may be releasably held in position bymeans of books 99. The construction is otherwise similar to thatillustrated in Figures 9 and and just described.

Referring now to Figures 14 and 15, the spider is adapted to be held inplace by turning the entire head, spider and all. An adapter block I05can be screwed onto the end of the flexible shaft mentioned. The frontend of the adapter block I05 is externally screw threaded, providinglarge, strong screw threads I06. An annular metal backing plate I01 hasan annular disc I08 of soft rubber cemented thereto. An under-cut ringI09 holds the adapter block I05 rotatably in position. Extendingforwardly from the backing plate I01 are a pair of plain pins IIO. Iprovide a spider assembly comprising an internally the parts relative tothe adapter block I05, thus screwing the assembly together.

It will thus be seen that there has been provided by this invention,sanding heads and flexible annular sanding discs having many practicaladvantages and according to which the objects hereinbefore set forth aresuccessfully achieved. As various possible embodiments might be made ofthe mechanical features of the above invention and as the art hereindescribed might be varied in various parts, all without departing fromthe scope of the invention, it is to be understood that all matterhereinbefore set threaded hub III to fit the thread I05 having spacedholes II2 to fit the pins III] and arms II3. To assemble this embodimentof the invention, sandpaper i placed on the annular disc I08, the spideris put in position with the holes II2 over the pins H0 and the hub IIIupon the screw I09 and then the entire unit is turned which rotatesforth is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. A sanding head comprising adapter means for attachment to a rotatablehollow shaft, said adapter means having a hole therethrough, an annularbacking plate concentrically attached to said adapter means, an annulardisk of flexible deformable rubber secured to said backing plate, therebeing radial recesses in the front face of the annular disk opposite thebacking plate, a plurality of arms each individually movable pivoted tothe backing plate, said arms being of a size to fit in the radialrecesses, and catches for the arms for removably securing them in theradial recesses in sandpaper holding position whereby to secure anannular disk of sandpaper to the flexible, deformable rubber formingcomplementary radial recesses .in the annular disk of sandpaper, wherebywater can flow through the hollow shaft, the adapter, the backing plate,the annular disk, and outwardly along the arms and the radial recessesto lubricate the sandpaper in use.

2. A sanding head comprising .metal disk means having a central axialhole therethrcugh, screw threaded means in said disk means forattachment to a hollow driving member, a flexible, soft, resilient,deformable pad of annular shape having an axial hole coinciding withsaid first mentioned axial hole, said pad being fastened to one side ofsaid disk means, a plurality of individually movable radial armspivotally attached to the metal disk means and radiating from the axisof said disk means, radial depressions in said flexible, soft,resilient, deformable pad radiating from the axis of said disk means,catches for said radial arms capable of securing all of them in saidradial depressions in sandpaper holding position, one in each of saiddepressions to hold a disk of sandpaper in said radial depressions andagainst said deformable pad, and said catches being releasable to permitan of the radial arms to be removed from said depressions by a.sufficient distance to allow a used piece of sandpaper to be removed anda fresh piece of sandpaper to be placed on said pad and secured inposition by the arms secured by the catches, said catches being all ofthem located on the same side of said disk means. as is the said pad,whereby water maybe directed axially through the disk and may flowoutwardly in the radial depressions, thus providing a copious supply ofwater to the sandpaper, and the head being capable of being furnishedwith fresh sandpaper by simply releasing the radial arms and fasteningthem again.

JOHN 0. mm.

